The present invention relates to a yellow pigment blend that may be used in traffic markings, particularly hot melt traffic striping. The resulting markings have very good heat resistance, light fastness, and meet applicable transportation regulations for color and retroreflectance.
Traffic markings can be applied to roadway paving surfaces by various methods, including hot spraying/extruding and via hot melt formulations. The methods and equipment used for applying traffic markings are well-known. Other paint formulations are usually solvent-based, though efforts to develop water-borne traffic markings have been initiated. A hot melt formulation typically contains a pigment blend and a polymeric carrier that has been liquefied. Specially designed equipment applies a layer of the liquid hot melt formulation over the road surface. The applied hot melt formulation layer is allowed to cool and thereby bond with the road surface to produce a permanent or semi-permanent traffic stripe or marking.
Traditional traffic paints use lead and hexavalent chrome pigments, which are toxic to plants, animals and humans and are subject to strict environmental regulation. Hence, an object of the present invention is to produce a lead and chrome-free yellow pigment blend that may be used to produce traffic markings.
Conventional organic pigment blends, when subjected to a hot melt heat test (temperatures of 400 to 450.degree. F. for a period of four hours), decompose and discolor. Accordingly, a further object of the present invention is a pigment blend that may be used in hot melt traffic markings, as evidenced by passing the hot melt heat test.
A further objective of the present invention is to obtain a blend of pigments having color properties complying with Federal, state, and local regulations for yellow traffic signals.
Other objects and advantages of the present invention will be clear to those skilled in the art upon closer inspection of the following disclosure.